1. Field of the Invention
The present invention relates to sensors. More specifically, the present invention relates to systems for detecting hazardous materials.
2. Description of the Related Art
Recent world events have revealed the need for early detection and interdiction of materials that can be used to construct weapons of mass destruction, i.e., explosives, biological and chemical agents, and nuclear materials. At the present time, the only comprehensive means of detection are random searches for which the probability of detection is small due to the limited sample set. Point solutions exist for the detection of various materials, such as an explosives detection unit. The cost, size, and limited throughput of these units, however, have limited their deployment.
Furthermore, inspections typically occur when materials are already at a vulnerable destination and the process of inspection may trigger detonation. Much of the recent interest in port security has therefore been directed towards monitoring the contents of cargo containers while in transit.
Cargo monitoring would require the establishment and maintenance of an RF link between a central monitoring system and each cargo container between the time the container is loaded on the shipping vessel and the time it reaches its destination. The RF environment in which this link must be established would be hostile, however, since in general the space between the two transceivers would be filled with large metal boxes stacked in close proximity (the cargo containers) housed inside another very large metal box (the hull of the ship). An RF signal can propagate only in the gaps between neighboring containers, and will encounter reflection-causing discontinuities at every turn. Clearly, it may not be possible to establish a direct link between any two transceivers in such an environment.
Hence, a need exists in the art for an inexpensive system or method for remote detection of multiple hazardous materials in cargo containers, and a system or method for communicating data acquired by detectors in cargo containers.